The present invention relates to a method of displaying a signal obtained by a measuring probe and a device therefor which is preferable to measure variables changing dependent upon a position of an object to be measured, by a measuring probe scanned on the object to be measured, and then display the measured values in a two-dimensional manner, and also the present invention includes a method of displaying surface flaw testing results and a device therefor which displays the magnitude of signals obtained by a surface flaw testing probe. In particular, the present invention relates to a method of displaying surface flaw testing results and a device therefor which is preferable to display the testing results of surface flaws such as cracks formed in or just below a surface of a cylindrical body of a metal such as a rolling roll, and a roller.
The flaws such as cracks formed in or just below a surface of a cylindrical body of a metal such as a rolling roll, and a roller are usually detected, as shown in FIG. 1, by putting a surface flaw testing probe (not shown) on a surface of a rotating cylindrical body 100, and then scanning the surface flaw testing probe in the axial direction of the cylindrical body to thereby carry out the flaw testing all over the surface of the cylindrical body. On this occasion, the above scanning is refereed to as xe2x80x9cthe spiral-scanningxe2x80x9d, because the locus which the surface flaw testing probe describes on the surface of the cylindrical body is, as shown in FIG. 1, shaped like a spiral having a pitch P which is dependent on a rotational speed of the cylindrical body and a feed speed of the probe.
Conventionally, the magnitude of signals obtained by the above-mentioned surface flaw testing probe is, as shown in FIG. 6 of Japanese provisional patent publication (Kokai) No.5-142215, displayed by scanning a surface flaw testing probe spirally on a rolling roll, comparing the amplitude of the signal with a predetermined threshold value while detecting the flaws, and displaying a black line, e.g. on a developed map of a roll when the amplitude of the signal is below the predetermined threshold value, or displaying no black line, e.g. on the developed map of the roll when beyond the predetermined threshold value to thereby discriminate the flaws.
However, the flaw-displaying method in Japanese Provisional Patent Publication (Kokai) No.5-142215 has a problem that so long as the amplitude of the signal does not reach the threshold value even if a small flaw signal is obtained, nothing is displayed. In other words, the threshold value is determined taking account of the amplitude of the flaw signal to be detected, the level of the detected signal obtained at a sound portion of the rolling roll, and the level of extraneous electric noise. Actually, the size and the shape of the surface flaw formed in the surface of the rolling roll are in a thousand different ways, thereby causing the magnitude of the flaw signal to change in great quantities. As a result, even if the flaw is so large as to be harmful, it may provide a small signal dependent on its shape.
On the other hand, setting the threshold value to a small value so as to detect the small flaw signal eliminates the overlook. However, the detected signals obtained at a sound portion of the rolling roll owing to the micro-structure or the surface roughness slightly differ with the rolling rolls, and also the extraneous electric noises vary according to the change of the working state of the electrical external equipment and the grounding state of the equipment which drives the surface flaw testing probe for detecting the flaws, which causes, if the magnitudes of the detected signals are high, the display to be made as if the flaws formed all over the surface of the roll.
Therefore, the threshold value is usually set with a margin with respect to the magnitude of the signal obtained at the sound portion of the rolling roll and the level of the extraneous electric noise (hereinafter generically referred to as xe2x80x9cxe2x80x9cthe noise levelxe2x80x9dxe2x80x9d), and also so long as amplitude of the signal does not reach the threshold value even if a small flaw signal which is slightly higher than the noise level is obtained, nothing is displayed.
The present invention has been made in view of the above-mentioned conventional problems. It is therefore an object of the invention to display small flaw signals, etc. when displaying the magnitude of signals obtained by a measuring probe, e.g. a test signal obtained by a surface flaw testing probe.
The present invention provides a method of displaying a signal in a two-dimensional manner, in which signal is obtained by one or more measuring probes relatively scanned on an object to be measured, characterized by comprising the steps of setting an administrative range with respect to the magnitude of the signal, selecting respective display colors used for displaying a signal falling in magnitude beyond the administrative range and a signal falling in magnitude within the administrative range from at least two different color regions which can be visually distinguishable in the color space, and displaying the measured results using the selected respective display colors while changing the color and/or, the depth of color according to the magnitude of the signal, which causes the above-mentioned problems to be resolved.
The color space can be represented by an L*a*b model of CIEL (International Commission on Illumination), an RGB model, or a CMYK model.
In particular, when one of the at least two different color regions which can be visually distinguishable comprises a black-and-white gradation (gray scale), or two of the at least two different color regions which can be visually distinguishable are complementary in color to each other, the magnitude of the signal can be easily discriminated.
Further, when the signal falling in magnitude beyond the administrative range is displayed using the gray scale according to the magnitude of the signal, and the signal falling in magnitude within the administrative range is displayed using colors within the respective color regions except the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal, the signal falling in magnitude within the administrative range and the signal falling in magnitude beyond the administrative range can be easily discriminated.
Besides, when the signal falling in magnitude beyond the administrative range is displayed using colors within the respective color regions except the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal, and the signal falling in magnitude within the administrative range is displayed using the gray scale according to the magnitude of the signal, the signal of magnitude within the administrative range and the signal of magnitude beyond the administrative range can be easily discriminated.
Further, when both the signal falling in magnitude beyond the administrative range and the signal falling in magnitude within the administrative range are displayed using colors within color regions different from each other without using the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal, any magnitude of the signal can be determined by colors.
The administrative range may have an upper limit value and a lower limit value, and it is possible to select three respective display colors used for displaying a signal ranging in magnitude from zero to the lower limit value, a signal ranging in magnitude from the lower limit value to the upper limit value, and a signal falling in magnitude beyond the upper limit value from at least three different color regions which can be visually distinguishable in the color space, and display the measured results using the selected respective display colors while changing the color and/or the depth of color according to the magnitude of the signal.
Or, the administrative range may comprise a greater part and a smaller part with respect to the threshold value, and it is possible to select respective display colors used for displaying a signal falling in magnitude ranging from zero to the threshold value, and a signal falling in magnitude beyond the threshold value from at least two different color regions which can be visually distinguishable in the color space, and display the measured results using the selected respective display colors while changing the color and/or the depth of color according to the magnitude of the signal.
Or, the signal ranging in magnitude from zero to the threshold value can be displayed using the gray scale according to the magnitude of the signal, and the signal falling in magnitude beyond the threshold value can be displayed using colors within the respective color regions except the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal.
Or, the signal ranging in magnitude from zero to the threshold value can be displayed using colors within the respective color regions except the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal, and the signal falling in magnitude beyond the threshold value can be displayed using the gray scale according to the magnitude of the signal.
Or, both the signal ranging in magnitude from zero to the threshold and the signal falling in magnitude beyond the threshold value can be displayed using colors within color regions different from each other without using the gray scale while changing the color and/or the depth of color little by little according to the magnitude of the signal.
The signal can be a signal obtained by a surface flaw testing probe.
The surface flaw testing probe can be a surface wave probe for detecting a flaw by receiving a echo from the flaw by use of surface waves propagated in a surface of the object, an eddy current testing probe for detecting a flaw by sensing the flaw-dependent change of an eddy current induced in a surface of the object, or a magnetic leakage flux sensor for detecting a flaw by sensing the flaw-dependent change of magnetic leakage flux.
The present invention provides a device for displaying a signal in a two-dimensional manner, in which signal is obtained by one or more measuring probes relatively scanned on an object to be measured, characterized by comprising a measuring probe relatively scanned on an object to be measured; a position detector of a measuring probe; a signal-processing device for processing a signal obtained by the measuring probe; and a computer, which enables the above-mentioned problems to be resolved.
The measuring probe can be a surface flaw testing probe, such as a surface wave probe, an eddy current testing probe, a magnetic leakage flux sensor.
According to the previously set administrative range, the computer can select respective display colors used for displaying a signal falling in magnitude beyond the administrative range and a signal falling in magnitude within the administrative range from at least two different color regions which can be visually distinguishable in the color space, and display the measured results while changing the color and/or the depth of color using colors within the respective color regions according to the magnitude of the signal.
In the present invention, the flaw testing results and the like are displayed using colors within different color regions selected from different color regions A to D as shown in FIGS. 2 to 4, which can be visually distinguishable in the color space when displaying, on the basis of a preset threshold value, the signal ranging in magnitude from zero to the threshold value and the signal falling in magnitude beyond the threshold value while changing the color and/or the depth of color little by little within each of the color regions according to the magnitude of the test signal. FIG. 2 shows a selection example of the different color regions in the color space, using a L*a*b color model of the CIE. FIG. 3 shows a selection example of the different color regions in the color space, using an RGB color model, and FIG. 4 shows a selection example of the different color regions in the color space, using a YMCK color model. In FIGS. 2 to 4, a color in the color region A comprises the depth of black-and-white color, i.e., the so-called gray scale, and the color regions B to D each comprises colors other than the gray scale.
For example, as shown in FIG. 5, the signal ranging in magnitude from zero to the threshold value is displayed using the gray scale (the color region A in FIGS. 2 to 4, e.g. a=0, and b=0 in the L*a*b color model of the CIE), i.e. the depth of color changing from white to black according to the magnitude of the signal, whereas the signal falling in magnitude beyond the threshold value is displayed using colors except the gray scale, e.g. colors from yellow to red (colors within the color regions except the color region A in FIGS. 2 to 4, e.g. axe2x89xa00, and Bxe2x89xa00 in the L*a*b color model of the CIE) while changing the color little by little according to the magnitude of the signal.
There is shown in FIG. 6 an example of thus displaying the flaw testing results on the developed map of the roll, and also in FIG. 7 an example of displaying the same flaw testing results by the conventional displaying method. Moreover, FIG. 7 shows the signal falling in magnitude beyond the threshold value by black color, and the signal ranging in magnitude from zero to the threshold value by white color, as is distinct from the case of Japanese Provisional Patent Publication (Kokai) No. 5-142215. This result is obtained from the rolling roll having artificial flaws and actual flaws in a surface thereof, by the spiral-scanning using the surface wave probe. FIG. 6 definitely shows that the small flaw signals, which have not been capable of being displayed by the conventional method, are clearly displayed. On this occasion, the reason why the displayed flaw is long in the circumferential direction is that the flaw is detected at plural times during the surface wave probe comes near the flaw.
Further, as shown in FIG. 8, the signal ranging in magnitude from zero to the threshold value can be displayed using color, e.g. from light green to green, within the respective color regions other than the gray scale according to the magnitude of the signal while changing the color and/or the depth of color little by little, and the signal falling in magnitude beyond the threshold value can be displayed using the gray scale, e.g. the depth of color changing from gray to black according to the height of the magnitude of the signal. Also as shown in FIG. 9, both the signal ranging in magnitude from zero to the threshold value and the signal falling in magnitude beyond the threshold value can be displayed using colors, e.g. from light green to green for the former, and from yellow to red for the latter, within color regions different from each other without using the gray color while changing the color and the depth of color little by little according to the magnitude of the signal.
Moreover, FIGS. 2 to 4 show three types of color models for expressing the color space; however, the color space-expressing method using the color model is not limited to the above three types. Different type of color models can be employed.